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Robust Fly-by-Wire under Horizontal Tail Damage by Dlamini, Zinhle
Published 2016Get full text
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Phosphate bonded wood and fibre composites by Amiandamhen, Stephen Osakue
Published 2017Get full text
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Page will reload when a filter is selected or excluded.- General 5 results 5
- Nigeria 5 results 5
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- Background: Melon seed obtained from the fruit of Colocynthis citrullus L. is widely used in Nigeria as a soup thickener. The seed has a high oil yield (42-57%) which has been largely unexplored as excipient in pharmaceutical formulations. Objectives: To evaluate melon seed oil as a drug carrier in emulsion using diclofenac as a model drug. Methods: Melon seed oil was extracted and the physicochemical properties were characterised. The emulsions were prepared using the traditional wet and dry gum methods, and all the emulsions were evaluated using viscosity measurements, creaming rate, and in-vitro drug release. Results: Melon seed oil had a pale yellow colour, with characteristic taste, and a neutral pH. Melon seed oil exhibited higher acid, saponification and ester values than castor oil but lower iodine value indicating an edible non-drying oil, unsusceptible to auto-oxidation. Both oils achieved a great degree of emulsification with globule size < 15mm μm. Emulsions of melon seed oil were generally less viscous with a higher degree of creaming compared to castor oil emulsions. Diclofenac emulsions prepared with melon seed oil, however, were more viscous and gave the highest release of diclofenac irrespective of the method of preparation. Only diclofenac emulsion prepared with melon seed oil using the wet gum method had > 70 % release within 45 minutes thus meeting the official specification. Conclusion: Melon seed oil functioned as a drug carrier for diclofenac. Thus, it will find application in pharmaceutical emulsions. 3 results 3
- Melon seed oil 3 results 3
- Ofada rice starch 3 results 3
- castor oil 3 results 3
- diclofenac 3 results 3
- drug carrier 3 results 3
- emulsion 3 results 3
- Alcohol 2 results 2
- Background: Harmful alcohol use is a modifiable risk factor contributing to the increasing burden of non-communicable diseases and deaths and the implementation of policies focused on primary prevention is pivotal to address this challenge. Policies with actions targeting the harmful use of alcohol have been developed in Nigeria. This study is an in-depth analysis of alcohol-related policies in Nigeria and the utilization of WHO Best Buy interventions (BBIs) and multi-sectoral action (MSA) in the formulation of these policies. Methods: A descriptive case study design and the Walt and Gilson framework of policy analysis was utilized for the research. Components of the study included a scoping review consisting of electronic search of Google and three online databases (Google Scholar, Science Direct and PubMed) to identify articles and policy documents with no language and date restrictions. Government institution provided documents which were not online. Thirteen policy documents, reports or articles relevant to the policy formulation process were identified. Other components of the study included interviews with 44 key informants (Bureaucrats and Policy Makers) using a pretested guide. The qualitative data were coded and analyzed using thematic analysis. Results: Findings revealed that policy actions to address harmful alcohol use are proposed in the 2007 Federal Road Safety Act, the Non-communicable Diseases Prevention and Control Policy and the Strategic Plan of Action. Only one of the best buy interventions, (restricted access to alcohol) is proposed in these policies. Multi-sectoral action for the formulation of alcohol-related policy was low and several relevant sectors with critical roles in policy implementation were not involved in the formulation process. Overall, alcohol currently has no holistic, health-sector led policy document to regulate the marketing, promotion of alcohol and accessibility. A major barrier is the low government budgetary allocation to support the process. Conclusions: Nigeria has few alcohol-related policies with weak multi-sectoral action. Funding constraint remains a major threat to the implementation and enforcement of proposed policy actions. 2 results 2
- Binary mixtures of microcrystalline cellulose MCC (A), and lactose (L) in ratios at 75:25, 50:50, and 25:75% respectively were prepared. The binary mixtures were subjected to microscopical analysis and density measurements. The mechanical properties of paracetamol tablets formulated with the above excipients were assessed for tensile strength, bonding capacity (using the Ryshkewitch-Duckworth relation) and friability, while drug release properties were assessed for disintegration and dissolution times. The dissolution profiles were fitted into dissolution model equations to determine release mechanism and similarity of release. Microscopic analysis showed that the lactose particles were large, crystalline, and acicular in shape whereas the MCC particles were smaller and irregularly shaped. The binary mixtures had particle shape and sizes in between the parent compounds. The particle size of A25:L75 however, was larger than that of the proprietary brand, Microcelac®. Bulk and tapped densities increased with increasing amounts of MCC in the binary mixtures while particle density had an inverse relationship. Tablets containing A75:L25 had the highest tensile strength and bonding capacity and lowest friability in comparison to other binary mixtures and Microcelac®. However, tablets containing A75:L25 did not show superiority to Microcelac® in terms of paracetamol release. Its release, however, followed the Korsmeyer-Peppas model indicating a super case II transport mechanism. Only comparisons of tablet combinations of Lactose: A25:L75 and MCC: A50:L50 had a similarity factor, f2 >50. Tablets made of A75:L25 exhibited the highest mechanical and release properties of the binary mixtures, as directly compressible excipient in comparison to the parent compounds and Microcelac®. This mixture, A75:L25 therefore, could be developed for commercial use in tablet formulations. 2 results 2
- Dioscorea starches 2 results 2
- Factorial design 2 results 2
- Health policy 2 results 2
- Organic Chemistry 2 results 2
- Public health 2 results 2
- Reliability indices are considered to be reasonable and logic ways to judge the performance of an electric power system. Reliability indices which are proposed by the IEEE are used to evaluate the performance of selected distribution systems on the national grid. Ten years of outage data (1998 - 2007) from seven selected distribution systems on the national grid were used as case studies in this research work. A generalized model is developed for a quantitative evaluation of relative indices of the national grid system. The development of the model stated with identification of the system reliability indices and estimating the contributions of system indices to the failure rate of the selected distribution system on the national grid. The computed system reliability indices are used as input parameters for the generalized model. Relative CAIDI index is computed by simulation using MATLAB 7.7 which automatically generates the graph of the relative CAIDl against names of feeders. The percentage average relative CAIDls for Ibadan, Port-Harcourt and Benin distribution systems are 71.86%, 52.79% and 75.79% respectively, thus, average reliability levels. Ilorin, Ikeja, Kaduna and Kano distribution systems have percentage average relative CAIDls of 11.95%, 39.76%, 40.17% and 41.08% respectively with poor reliability levels. With the aid of curve fitting (cf) tools, two distinct model equations were developed from which a generalized model is formulated for a quantitative evaluation of reliability indices of the national grid. The generalized model is a polynomial function whose order depends majorly on the level of industrialization of the distribution systems and the number of distribution feeders. 2 results 2
- "Mathematics has diverse applications as decision making tool. This study investigated the use of a proposed pure mathematical formulation (i.e. excluding human factor) for citing appropriately the location of political capital ci of an inhabited designated area. Digitized data of Scale map of Nigeria as a case study was used as input to a FORTRAN 90 programme codes of an equivalent least squares method mathematical formulation. The resulting simultaneous equations involving the political capital city coordinates as unknown variables were solved using Gauss Elimination Algorithm. The political capital city Cartesian coordinate prescribed as (26, 24) in grids unit for the studied case of scale map of Nigeria compared visually satisfactorily with Abuja location on the Map. The Nigeria land area cover was under-estimated by 2.3% referencing 923,768 sq km obtained from Microsoft Encarta Premium (2009). Similarly the Nigeria coastline was estimated. as 25.3% of the country's estimated perimeter (3369 krn). This mathematical tool can be used to cite the centrally located capital city or capital city relocations economically, timely, accurately and reliably. This programme can also be used for citing of capital cities for other countries and center of any irregular shapes on two dimensional plane. " 1 results 1
- "Optimal allocation of products to downstream locations is a major requirement for minimizing the distribution costs associated with supply chain systems. Unfortunately many supply chain managers rely on their intuition and feelings to make these allocation decisions. In this study a mathematical model was developed for minimizing the distribution cost in a multi-product 2-echleon supply chain system. The distribution system of a leading bottling plant in Nigeria was studied to understand the underlying supply chain system . Attempt was made to identify system parameters, variables, limitations, criteria so as to be able to define the distribution problem The interactions and flow of products in the system were identified and characterized as a 2 echelon supply chain system. Mathematical model of the system was developed. The problem model, a linear program formulation with three major constraints; demand, availability and company policy requirements was parameterised based on demand data product availability data, company policies and unit transportation costs to various downstream locations. The model was solved for a 12 product 8 destination case. It was observed that the model application produces 6% reduction in the distribution cost compared to the existing practice of the company. It is concluded that the model is effective to reduce or minimize distribution expenses for any multiproduct multiple destination system and fulfilling demand at various destinations. " 1 results 1
- "Road bumps play a crucial role in enforcing speed limits, thereby preventing overspeeding of vehicles. It significantly contributes to the overall road safety objective through the prevention of accidents that lead to deaths of pedestrians and damage of vehicles. Despite the importance of road bumps, very little research has been done to investigate into their design. While documentation exists on quantitative descriptions of road bumps, they offer little guidance to decision making. This work presents a unique approach to solving road bumps design problems. The results of our study reveal three important road bumps variables that influence the control of vehicle speeds. The key variables are bump height, bump width, and effective distance between two consecutive road bumps. Since vehicle speed control is the ultimate aim of this study the relationship between vehicle speed and other variables earlier mentioned is established. Vehicle speed is defined as the product of frequency at which a vehicle is moving over road bumps and the sum of effective distance between two consecutive road bumps. In the determination of bump height we assume a conical shaped curve for analysis as a matter of research strategy. Based on this, two stages of motion were analysed The first concerns the motion over the bump itself while the second relates to the motion between two consecutive road bumps. Fourier series was then used to formulate a holistic equation that combines these two stages. used trigonometric functions to model the behaviour of the first stage while with the second stage giving a functional value of zero since no changes in height are observed. We carried out vibration analysis to determine the effect of road bumps on a vehicular system. Arising from this a model component is referred to as an isolation factor. This offers guidance to the safe frequency at which vehicles could travel over road bumps. The work appears to contribute to knowledge in road bump research through the development of a novel approach to the control of vehicle speeds. Significant research progress could be made if engineering and academic communities at large appreciate our viewpoints. With this work it is apparent that varying of the assumptions made in terms of bump shape may produce high proliferation of beneficial research studies. Although this work may reveal a new way of investigation into road bump research, no claim is made for the work comprehensiveness. We expect experts to challenge some of our thoughts and ideas presented in this work " 1 results 1
- "This investigation derived its strong motivation in the adoption of versions of second-order Runge-Kutta methods where there is presently dearth of relevant literature to re-establish .the complicated nature of solution of buffing oscillator dynamics. The choice of second-order Runge-Kutta methods hinged On its simplest algebraic formulation of relevant coefficients based on Taylor series expansion comparing with its higher order counterpart. Validation of FORTRAN-90 codes of algorithms was achieved by phase plots comparison reference to Dowell (1988) as standard. The nature of simulated solutions were visually determined with scatter plot of phase variables obtained from simultaneous implementation of large number of versions of second-order Runge-Kutta methods in conjunction with the corresponding literature results. Validation results are acceptable to within the accuracy limit of Runge-Kutta methods adopted. The scatter plots on phase plane for cases investigated are well structured and bounded (strange) and compare correspondingly well with literature Poincare sections. This investigation re-establishes the complex nature of solution of Duffings oscillator dynamics. Its established procedures provide an alternative Poincare section method and can be utilised for preliminary verification of system dynamics behaviour subject to confirmation by additional dynamics tests. " 1 results 1
- "This work considered the unsteady state drainage of fluid from a vertical column of porous material of varying porosities in an attempt to verify variation of drawndawn surface with porosity and time using riverbed sand. Kerosene was used as the flowing fluid. Mathematical assumptions ware made in connection with Darcy's law. The result showed that the experiment which was designed from the theoretical framework agreed with the theory to a large extent, However, this is not in perfect agreement with an earlier experiment which was performed using well rounded beads in which glycerine was used as the flowing fluid. A FORTRAN program was written to study the variation theoretically and this was compared with the experimental result. There exists, a degree of discrepancy between theory and experiment indicating that, the mathematical formulations did not perfectly agree with the complex earth system as compared with the bead model that was initially used. There is a need for the modification of the mathematical formulations; nonetheless, an unsteady drawndown, pattern was attained with different porosity even in medium with very complex geometry. " 1 results 1
- "This work investigated the distribution of Von Misses stress in LNG Spherical Carbon Steel Storage tanks. Using the Finite Element Method and equations of elasticity, constant thickness carbon steel spherical storage tanks of 40 in. dia. 70in. dia of 1 in. shell thickness were subjected to different loading conditions from 500 to 4000Psi in incremental of 500 Psi. Spherical triangular elements based on shallow shell formulation were used for the model. The element has five degrees of freedom at each corner node, which are the essential external degrees of freedom without the degree of freedom associated with the in-plane shell rotation. The displacement fields of the element satisfy the exact requirement of rigid body modes of motion. The FORTRAN 90 coding was developed to obtain maximum Von Misses stress distribution with the tank subjected to different internal pressure and wind loadings. The results were then compared with the yield stress of the material of the tank. Von Misses stress is used as yield criteria whether to change tank material or increase the shell material thickness if yield stress is higher than the Von-Misses Stress. Results showed Von Mises stresses for a 40 in dia. Spherical shell with 1 in shell thickness able to withstand internal pressure loading alone up to 3500 Psi after which the shell thickness will no longer be able to withstand the loading. The 70in. dia. Vessel could only withstand internal pressure loading up to 2000 Psi. Validation of Finite Element modeling was done using ASME Section VIII Div 1 standard. Modeled results were observed not to be significantly different from ASME values (P>0.05). External wind effects alone on small dia. vessels was seen to be constant for all sides of the pressure vessel. 1 results 1
- A considerable fraction of sand in Niger Delta Area of Nigeria is contaminated with crude oil. The contaminated sand is largely utilised by local contractors for the production of concrete. However, there is need to establish its suitability in concreting. Previous works have centered on hardened uncontaminated concrete in crude oil environment but not on concrete made with Crude Oil Contaminated Sand (COCS). This research was designed to evaluate the effect of COCS on some engineering properties of fresh and hardened COCS concrete. Levels of crude oil contamination were determined using gravimetry method of Total Petroleum Hydrocarbon (TPH) test on nine sand samples randomly collected from some oil spill sites in Rivers State. Based on the test results, seven types of artificially contaminated sand were prepared with crude oil levels of 0.0, 2.5, 5.0, 10.0, 15.0, 20.0 and 25.0%. Workability (slump, compacting factor and flow), compressive strength, linear shrinkage, water absorption, and fire resistance were determined using concrete cubes, flexural strength using concrete beams, and surface resistivity using concrete cylinders in accordance with standard methods. Data obtained were analysed using ANOVA at p = 0.05. Eight models were developed using historic response surface methodology to predict the engineering properties of COCS concrete at water-cement ratio (w/c) of 0.5. Also, COCS concrete design mixes with contamination level and w/c ratio suitable for reinforced concrete were formulated. The TPH varied from 8.6 ± 0.2 to 14.1 ± 1.3%. The workability of concrete was improved by the presence of COCS. Slump, compacting factor and flow of the fresh concrete increased with increase in contamination from 30.0 to 200.0 mm, 0.5 to 0.9 and 15.0 to 85.0%, respectively. Compressive strength, flexural strength, linear shrinkage and water absorption of the hardened concrete reduced with levels of contamination from 31.5 ± 2.3 to 3.5 ± 0.0 N/mm2, 5.9 ± 0.8 to 0.1 ± 0.0 N/mm2, 0.1 ± 0.0 to 0.0 cm and 0.2 to 0.0 kg respectively. At a temperature of 200.0˚C, the percentage strength reduction increased from 18.4 to 94.8% for 2.5 to 25.0% contamination. Surface resistivity ranged from 25.1 ± 0.2 to 32.3 ± 0.2 kΩ-cm. The compressive and flexural strengths of COCS concrete were reduced by more than 50.0% at crude oil contamination level greater than 10.0%. The water absorption and surface resistivity values indicated that COCS concrete exhibited greater resistance to water and chloride penetration respectively, it shrank less when compared with the uncontaminated concrete, but exhibited poor fire resistance. Coefficient of determination, R2, of the models developed ranged from 0.823 to 0.999. Concrete design mix ratio of 1part of cement to1.6 part of COCS (10.0% crude oil) to 2.4 part of coarse aggregate was found to be appropriate at 0.45 w/c. This mix gave minimum compressive strength of 21.0 N/mm2 which is acceptable for reinforced concrete structures. Concretes produced with sand contaminated with less than ten percent crude oil were found suitable for use in low strength structures. Mix re-design using lower w/c improved the strength of the concrete. 1 results 1
- A non-pre-emptive goal programming (NGP) model for weld-metal chemical composition optimization from welding-flux ingredients is proposed. The proposed model, which is the first multi-objective mathematical programming approach to welding-flux formulation, provides increased flexibility to the welding-flux formulator in several ways: (1) several conflicting objectives can be simultaneously considered, (2) the best compromise for welding-flux formulation can be achieved with minimal expenditure of resources and experimental efforts, (3) the welding-flux designer can explore various trade-off options, and (4) the lead time and cost of developing welding consumables can be drastically reduced. This paper has extended the work of Kanjilal and co-investigators by coupling it with the NGP optimisation technique so as to prescribe the welding-flux ingredient levels that will achieve optimum performance for the flux at minimum experimental efforts and cost. The feasibility and suitability of the model is illustrated with data from the literature. 1 results 1
- Aceclofenac tablets 1 results 1
- Aceclofenacsodium 1 results 1
- Acid-modification 1 results 1
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